Consider the conditions of Example 11.6, but with the continuous fin arrangement of figure used in lieu of the circular fins of figure. The heat exchanger core is fabricated from aluminum, and the tubes have an inside diameter of 8.2 mm. An inside convection coefficient of 1500 W/m² ∙ K may again be assumed for water flow through the tubes, with combustion gases at 1 atm and 825 K in cross flow over the tubes. For a gas flow rate of 1.25 kg/s and a frontal area of 0.20 m², what is the gas-side overall heat transfer coefficient? If water at a flow rate of 1 kg/s is to be heated from 290 to 370 K, what is the required heat exchanger volume? Hint: Estimate the fin efficiency by assuming a hypothetical circular fin of radius r₂ = 15.8 mm for each tube. You may use the aluminum and fluid properties provided in Example 11.6.